(1) Field of the Invention
The present invention relates to vaporized fuel processing device and method which temporarily hold vaporized fuel generated in a fuel tank by means of an adsorption material installed within a canister, to supply vaporized fuel into an engine by purging the fuel corresponding to the vaporized fuel from the adsorption material during an operation of an engine, and, particularly, relates to the vaporized fuel processing device and method which can achieve an improvement in an efficiency of the engine.
(2) Description of Related Art
In such a kind of vaporized fuel processing devices as described above, a purge air is introduced into the canister through an intake air negative pressure of the engine. The purge air purges a fuel held on the adsorption material so that a latent heat of an evaporation causes the material to be cooled. Then, the fuel becomes difficult to be purged from the adsorption material. To avoid this difficulty, an electric heater made of a, so-called, PTC (Positive Temperature Coefficient) thermister serves to heat the adsorption material so that a purge efficiency is improved. This process is described in a Japanese Utility Model Registration Application Publication No.showa 58-111348 published on Jun. 29, 1983.
In a previously proposed vaporized fuel processing device disclosed in the Japanese Utility Model Registration Application Publication, a switching on or off of an electric power supply to an electric heater is carried out in response to an intake air pressure to the engine in the same way as a purge control valve. At the same time when the start of introduction of the purge air into the canister, On or off operation is carried out when the power supply to the electric heater has been started. At the same time when the purge air introduced into the canister, the power supply to the electric heater is started.